The present invention relates to a method of shrink film wrapping of one or more objects, in which two film webs, a first and a second web, are sealed together by means of a sealing device and in which the objects are moved in towards the sealed film webs with the aid of a pusher in one or more rows, whereafter the film webs are once again sealed together, cut off and caused to surround the objects, the first film web being provided with decorative artwork in register.
One common method within the packaging industry of making distribution units is to shrink film wrap one or more packages together to form a distribution unit which is attractive to the consumers. It is also becoming increasingly common that these distribution units wrapped with shrink film are given their own, distinctive identity by utilising a film carrying pre-printed decorative artwork.
The commonest method of shrink film wrapping is that the packages are surrounded by one or two film lengths forming a relatively loose bandoleer which, in a subsequent working station, passes a hot air oven where the film bandoleer is inflated by the hot air, whereafter the film is shrunk around the packages. The shrinking often entails that the film becomes creased and punctured during this process. Providing such a shrink film with any form of printing at all has proved to be extremely difficult.
Recently, use has begun to be made of so-called stretch film for wrapping packages into distribution units. As a result of this process, use is made of the stretching properties of the film instead of its ability to shrink when heated. This gives many advantages in that it is possible to utilise a thinner film, material consumption is reduced and, when the intention is to employ pre-printed film, neat and attractive packages will be obtained. An apparatus for shrink film wrapping which utilises such film is disclosed in Swedish Patent Specification SE 507 029. However, this apparatus has suffered from drawbacks when pre-printed film with register maintenance has been employed, since it has proved to be difficult to set and maintain it in register, given that the apparatus for register maintenance has but a very short time at its disposal to compensate for the position of the printed film in relation to the wrapping of the packages.
One object of the present invention is to realize a method of shrink film wrapping of objects, for example packages, which, in a simple and reliable manner, makes for the use of pre-printed film which is held in register.
A further object of the present invention is that the method gives a sufficiently long time interval for the apparatus to be able to compensate for the position of the film in relation to those packages which are to be surrounded by the film.
These and other objects have been attained according to the present invention, in that the method of type disclosed by way of introduction has been given the characterizing feature that the first film web is held in register in that the first film web is caused to form a loosely hanging loop before each sealing operation.
Preferred embodiments of the present invention have further been given the characterizing features as set forth in the appended subclaims.